Saturday, August 1, 2015

Science Links: 8/1/2015

Article #1: How Far Can the Human Eye See a Candle Flame?
The brightest stars, such as Vega, have a [apparent] magnitude 0. At what distance would a candle flame be comparable to a star like Vega, they asked. 
Some straightforward nighttime experiments with a candle suggested that the distance was 338 meters. “To our eyes the candle flame and Vega appeared of comparable brightness,” they say.
This is apparent magnitude. So, at 338 meters (about 370 yards or 0.2 miles) Vegas and a candle would be equally bright.

They compared the magnitude of the dimmest stars we can see with how far away the candle had to be in order for it to have the same magnitude. That distance was about 1.6 miles

Article #2: Earth's 'magnetic personality' much older than previously thought

By measuring the magnetic field of magnetite from Australian zircons, researchers concluded that the magnetic field of earth was at least or 4.2 billion years old. Or it has existed for at least 80% of earth's history.

Article #3: California ‘rain debt’ equal to average full year of precipitation

California averages about 20 inches of rain a year, but the actual amount in any given year swings fairly wildly.

California regularly experiences drought years, but this is the third year running that there has been a rain debt and the total over the last 3 years equals 1 year.

California has had larger rain debt, for example, "a 27.5 inch deficit of rain and snow occurred in the state between 1986 and 1994."

That was less of a crisis than today because the population was smaller, less agriculture was irrigated, and less water was diverted for environmental purposes.

There is a good discussion of the mechanics of the flow of air which creates both drought and surplus conditions, along with a discussion of how El Nino plays into the atmospheric dynamics.

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